Apparatus for continuous casting



Feb- 7, 1957 J. wooDBURN, JR

'APPARATUS FOR CONTINUOUS CASTING 5 SheetsSheet l Filed DeO. 5. 1963 2 2 [Q -|\2 Ml, Z wav a\\@\w\\\\ \\\\\\W A s/ WM^A\\\ m v\\ m w m Q@ N C \\v\\%\\@\\\\\\ @\\&\ \W\\\\M\^\ f .INVENTOR Q5 BVG/@Z yf, MM jy,

J. WOODBURN, JR

APPARATUS FOR CONTINUOUS CASTING Feb. 7, 19.67

s sheets-sheet 2 Filed Deo. I5, 1963 Feb. 7, 1967 J. WOODBURN, JR 3,302,252

APPARATUS FOR CONTINUOUS CASTING Filed Dec. 5, 1965 3 Sheets-Sheet 5 9U i f Qa' .6i

I NVENTOR.

United States Patent O 3,302,252 APPARATUS FOR CONTINUOUS CASTING James Woodburn, Jr., Wheaton, Ill., assignor to Amsted Industries Incorporated, Chicago, Ill., a corporation of New Jersey Filed Dec. 3, 1963, Ser. No. 327,641 2 Claims. (Cl. 22-57.2)

The present invention relates to apparatus for and method of continuous casting.

A broad object of the invention is to attain advantages resulting from continuous casting, the method including continuously adding molten metal and continuously withdrawing the cast article at a corresponding rate, both of indefinite duration within practical limits, with consequent economy in the molded product.

The invention relates more particularly to casting apparatus and method wherein the cast product is formed in an upward movement through a mold and from which the molded product continues to move in an upward direction and is withdrawn in that direction from the mold.

A principal advantage of the invention is related to the upward withdrawal of the molded product in that there is no necessity for providing means for preventing stray passage of molten metal through the mold, as would be the case where the molded product is withdrawn downwardly.

Another and more specific advantage of the invention is that due to the advantage just mentioned, namely the elimination of the necessity for preventing stray passage of the molten metal, the molded product may be in hollow or tubular shape, such as pipe, and upon withdrawal of the pipe the molten metal remains below the top of the mold due to gravity.

Another object of the invention is to provide a novel apparatus containing a heated ladle and a cooled mold closely associated, both in function and physically, whereby the molten metal in the ladle remains molten until it passes into the mold where it is gradually cooled and freezes, forming the desired molded product.

Another object is to provide apparatus including means for oscillating the mold, relative to the rate of withdrawal of the molded product, whereby to facilitate movement of the molded article through the mold, and more specifically to provide greater eciency with respect to the frictional engagement and relative movement between the molded product and mold.

A still further object is to provide means for oscillation of the molten metal in the mold whereby to provide a more precise or clearly defined inner surface of a hollow molded product such as pipe.

Still another object is to provide apparatus for and method of continuous casting wherein novel means is provided for continuously adding molten metal to the apparatus to enable indefinitely continuous casting.

Other objects and advantages of the invention will appear from the following detailed description taken in conjunction with the accompanying drawings, wherein:

FIGURE l is a vertical sectional view of one form of apparatus embodying the features of the invention;

FIGURE 2 is a vertical sectional view of another form of apparatus;

FIGURE 3 is a fragmentary sectional view of a por- 4tion of mold apparatus including means for oscillating the mold, with the mold in retracted position;

FIGURE 4 is a view similar to FIGURE 3, but with the mold in advanced position;

FIGURE 5 is a detail sectional view of a starter section, located in the mold, utilized for starting with drawal of the molded product;

3,302,252 Patented Feb. 7, 1967 FIGURE 6 is a diagrammatic view of a means for cutting the molded product in lengths;

FIGURE 7 is a diagrammatic view of another means for oscillating the mold; and

FIGURE 8 is a diagrammatic view of still another means for oscillating the mold.

Referring now in detail to the drawings, attention is directed first to FIGURE 1 showing one form of apparatus embodying the features of the invention. The apparatus includes a pouring tank 12 which may be of any suitable construction, defining a cavity 14 in which is disposed a ladle 16. The tank 12 may have an opening at any location such, for example, as at the top in the present instance, and is provided with a ange 18 around the open top, for use in securing a cover 20. The cover 20 may be secured in place by any suitable means such as clamps 22, there being a sealing gasket interposed between the cover and the flange 18 for sealing the interior of the tank against the escape of air which is introduced into the tank for pressure pouring.

Communicating with the interior of the tank is a suitable conduit 24 leading from a conventional pump or other air pressure developing apparatus indicated here diagrammatically which, upon controlled operation thereof, develops air pressure in the tank for pressure pouring of the molten metal.

The ladle 16 includes bounding elements composed of insulating refractory material 28, and embedded in the upright wall elements thereof is an induction coil 30 for connection with a suitable source of current (not shown) for induction heating the ladle and the molten metal 32 therein, and maintaining it in molten form.

A pouring tube 34 leads from adjacent the bottom of the ladle, such as in or adjacent a cavity 36 in the bottom of the ladle, upwardly out of the ladle and through the top cover 20 where it communicates with the mold indicated generally at 38, which will be described in detail below herein. For convenience in supporting the pouring tube in position, the upper end thereof is provided with a flange 40 which engages and rests on the outer surface of the cover 20. A plate 42 is disposed on the cover 20 for supporting and adapting the mold 38, the plate having a recess for receiving the ange 40 and the upper extremity of the tube 34 which projects above the flange. The mold 38 includes a central sleeve portion 44 provided with a central vertical bore 46 forming a cavity in which the molding of the product takes place. Preferably, the inner diameter of the pouring tube 34 is the same as the diameter of the cavity 46 to facilitate flowing of the molten metal.

The sleeve 44 is of high heat conductivity for conducting the heat from the molten metal therein for freezing it and producing the molded product. Preferably, the sleeve is made of graphite, and Aits outer surface is preferably conical in shape tapering downwardly and supported in a cooling packet 48 which may be of copper. The cooling jacket 48 has `an annular internal space 50 for circulation of a cooling liquid, such as water, for hastening the cooling action of the molten metal. Water is forced therethrough by suitable means indicated diagrammatically at 52 which may withdraw water from a tap, and force it through an inlet conduit 56, and after passing through the interior space 50, it passes through the outlet conduit 54 to waste. A suitable top plate 58 may be utilized for retaining the graphite sleeve 44 in the cooling jacket.

The molten metal 32 is placed in the ladle 16 in any suitable manner, and then the ladle is placed in the tank 12 and the induction coil 30 connected with a suitable source of electrical supply. In the present instance, it is lowered through the open top of the tank, after which the cover 22 is secured in place, the mold 38 being carried by 3 the cover or later applied thereto, as desired. After the ladle is thus introduced in the tank, air pressure is developed in the tank by the means 26, and due to the sealed condition of the tank the air pressure forces the molten metal 32 downwardly in the ladle and upwardly through the pouring tube 34, and thus into the mold.

I have provided novel means for starting the molded product in the withdrawing action, namely a starter section 60, shown in detail in FIGURE 5. This starter section may be in the fo-rm of an inverted cup having an open lower end with a plurality of cutouts or notches 62 in its lower marginal edge, and is provided with an extension 64 by which a line or cable 66 may be secured. It is lowered into the mold to a position indicated in FIGURE 5, in which its lower end is immersed in the molten metal, the level of the latter being indicated by the line 68. The starter section 60 may be made of a metal having a melting point higher than that of the metal being cast, eg., steel having a melting point of in the neighborhood of 500 F. higher than cast iron. The cooling action on the molten metal in the mold will already have been started, and the metal being cast when it freezes will grip the starter section 60 with sufficient mechanical force to be withdrawn by the starter section when the latter is raised. The cooling water passed through the cooling jacket continues the freezing operation, the outermost portion of the column of molten metal in the mold cavity being frozen first in an annular or pipe form. The starter section is then withdrawn by suitable hoist means (not shown) withdrawing the molten product or pipe.

After the molded product or pipe has been thus started, the withdrawing action is continued with a plurality of extraction rollers 70 frictionally engaging the pipe, which upon rotation thereof (by suitable means not shown) kin the directions indicated, withdraw the molded product or pipe now identified at 72. It will be understood that the peripheral speed of the extraction rollers is such as to withdraw the molded product at the desired rate according to the desired rate of molding, taking into consideration all other factors affecting the molding operation. The Irate of withdrawal of the moldedproduct or pipe 72, together with the temperatures involved, determines the wall thickness of the pipe, it being understood that a slower rate of withdrawal results in a thickner-walled pipe, other factors being equ-al. Similarly, a different temperature of molten metal will result in different wall thickness, other factors being equal, and the same is true with respect to the temperature of the cooling water in the cooling jacket 48 and the rate of fiow thereof.

It lis desired to cut the molded pipe in lengths and to do so without stopping or otherwise interfering with the constant withdrawal of the molded product. To accomplish this end, the cut-off device is arranged to move upwardly with and at the same rate as the molded pipe. Any of various arrangements may be utilized for this purpose, one being shown diagrammatically in FIGURE 6, where a pulley 74 is driven at a peripheral speed equal to that of the extraction rollers 70. A cable 76 is trained over that pulley and over a series of other pulleys 7S, the opposite ends of the cable being connected above and below respectively to a cutting means indicated generally at 80, including a cutting element 82 for cutting the pipe. Upon rotation of the pulley 74 in the appropriate direction, clockwise in the arrangement shown, the cutter means 80 is elevated with the pipe. The cutter element 82 during this operation is operated and moved against the pipe, cutting the latter. Suitable means may be employed -for controllably operating the pulley 74, such as mounting it on a common shaft with one of the extraction rollers, and providing a clutch means for controllably elevating the cutter means. The cutter means may be lowered by any suitable means such as by gravity.

The embodiment illustrated in FIGURE 2 includes the principal features included in the apparatus of FIGURE l, with additional features described below. The apparatus of FIGURE 2 includes the tank 12, ladle 16, pouring tube 34, and mold 38. Instead of the single inlet conduit 24, there is in addition an outlet conduit 84 for controlling the fiow of compressed air in and out of the tank 12. Suitable pump means 86 is provided for pumping compressed air into the tank through the inlet conduit 24 and controllably removing it therefrom through the outlet conduit 84 for controllably varying the air pressure in the tank.

In addition to the various structural elements incorporated in the apparatus of FIGURE 1, there is also a vertical filling tube 88 which extends through the cover 2f) and terminates closely adjacent the bottom of the ladle, and has a filling hopper element 90 at the top exteriorly of the tank. The filling tube is, of course, sealed in the cover 20 to prevent escape of air from the tank therepast. An induction coil 92 surrounds the upper exposed portion of the filling tube for heating and maintaining in the molten state the portion of the molten met-al that extends up into the tube, as it does in the normal operation of the apparatus.

In the operation of the `apparatus of FIGURE 2, the molten metal is poured into the filling tube 88 until the level in the ladle rises to the desired height, such as adjacent the top thereof. Then air pressure is developed in the tank, which forces the molten metal up through the pouring tube 34 and into the mold 38, and the molding operation is performed and continued as described above in connection with FIGURE l. The molten metal also rises in the filling tube 88, due to the air pressure, to Ia level effectively equal to the level of the liquid portion of the molten metal in the mold, and as the molding or casting operation is continued, the withdrawal of the metal from the mold is compensated by additional molten metal forced thereinto by the air pressure which is constantly increased to maintain the desired level of molten metal in the mold.

An advantage of the invention is that oscillation of the molten metal can be effected. This is done by varying the air pressure in the tank. For example, if lthe air pressure is increased to a predetermined value, it may raise the level of the metal in the mold to a height indicated by the line 68a, and upon release of that pressure to a second and lower predetermined value, the level of the molten metal descends to a position, for example, indicated by the line 6Sb. This lowering of the level is done relatively rapidly, causing a washing effect of the molten metal in the center of the pipe against the inner surface thereof, producing a more refined and clean-cut inner surface of the pipe. It will be understood that the lower limit indicated by the line 68b would be above the lowermost limit of any freezing effect in the molded product.

The upper end of the filling tube 88 is at least as high as the upper extremity of the mold so as to prevent overflow of the molten metal through the filling tube in the normal operation of the apparatus. The arrangement enables continuous filling or replenishment of the apparatus; for example, given a constant air pressure in the tank, molten metal may be introduced into the filling tube and the level resulting therein forces the metal up into the mold, and at the same rate at which the metal is introduced in the filling operation.

The apparatus is also adapted for reciprocation of the mold relative to the other portions of the apparatus and relative to the rate of withdrawal of the pipe. FIG- URES 3 and 4 show a fragmentary portion of the apparatus incorporating means for oscillating the mold. these figures, the mold 38 is provided with a surrounding flange 94 or a plurality of extensions at its lower end and another flange 96 or extensions at its upper end. Tie bolts 98 interconnect these two anges for forming a rigid assembly of the various components of the mold, and the lower flange 94 provides means for securing the pouring tube 34 to the mole.

This rigid mold assembly is detachably supported on an extension 100 which is annular in form and mounted 0n the top 20 of the tank. This extension 100 receives the upper end portion of the pouring tube 34 f-or reciprocating movement therein, a suitable bushing 102 being secured as by Welding to the pouring tube for sealing around it against the escape of the compressed air. The bushing 102 is secured to an outer bushing 103 and the two together rise and fall with the pouring tube and mold assembly. The bushing 103 has bearing engagement with a surrounding wall element 105 included in the extension 100.

Power means, such as a plurality of hydraulic ram means 104, is provided for raising the mold. These ram means are mounted on the cover 20 .and have pistons 106 engageable with the lower ange 94. Upon extension of the rams 106 through suitable power means (not shown) the flange 94 and thus the mold assembly is raised, carrying also the pouring tube 34 therewith.

The mold assembly is raised to its upper limit at a rate equal to that of the withdrawal of the molded pipe, and then abruptly lowered while the pipe continues to be withdrawn at its normal rate. This oscillating action frees the pipe from the mold, thus minimizing the static friction adherence of the pipe to the mold. This action results in greater average freeing action relative to Ia fixed mold and constant movement of the molded product or pipe.

It Will be understood that the power ram means 104 is exemplary of various means that may be utilized for oscillating the mold. For example, as shown in FIG- URE 7, cam means 108 may be provided for engaging a suitable element 110 of the mold 38, and upon rotation of the cam in the direction indicated, the mold will be raised. The cam is provided with a drop-off surface 112 enabling an abrupt lowering of the mold, it being understood that the surface 112 may have a slight inclination to prevent an entirely free fall of the mold.

FIGURE 8 diagrammatically illustrates still another form of means for oscillating the mold. Instead of the cam 108, a saw tooth member 114 may be utilized, each tooth 116 having a slope such that upon movement of the member 114 in the direction indicated and Aat a predetermined rate, the teeth will engage the element 110 and raise the mold at a rate equal to the Withdrawal of the molded product or pipe, and upon the tooth passing beyond the element 110, the mold drops, as described in connection with FIGURE 7,

While I have herein shown certain preferred forms of the invention, it will be understood that changes may be made therein within the scope of the appended claims.

I claim:

1. Apparatus for continuous casting comprising a ladle, a mold above the ladle and having a vertical passage therethrough forming a cavity, means forming a passage from said ladle to and communicating with said mold cavity at the lower end thereof, said mold being of high heat conductivity relative to the ladle and passage forming means, means for applying pressure lon the molten metal in the ladle for forcing the molten metal through said passage and into said mold, means for continuously withdrawing the cast product at a constant rate from the upper end of the mold, and means for oscillating the molten metal and thereby raising and lowering the level thereof in and relative to said mold, said last mentioned means being operative for raising that level at .a rate substantially equal to the rate of withdrawal of the cast products and abruptly lowering the level independently of and during the constant withdrawal of the cast product.

2. The apparatus set out in claim 1 wherein the pressure applying means includes means for controllably varying the pressure so as to oscillate the molten metal and thereby raise and lower the level thereof in the mold.

References Cited bythe Examiner UNITED STATES PATENTS 2,135,183 11/1938 Junghans 22--57.2 2,163,967 6/1939 Strawn et al.

2,356,013 8/1944 Spooner 22-79 X 2,473,221 6/1949 Rossi 22-57.2 2,569,150 9/1951 Brennan 22-200.1 2,871,530 2/1959 Wieland 22-572 2,955,334 10/1960 Pulsifer 22-57.2 3,045,299 7/ 1962 Steigerwald 22-572 3,124,855 3/1964 Baier 22-200.1 3,170,205 2/1965 Brown 22-2001 3,201,837 8/1965 Sylvester 22-69 FOREIGN PATENTS 1,241,931 8/ 1960 France.

I. SPENCER OVERHOLSER, Primary Examiner.

R, S, ANNEAR, Assistant Examiner. 

1. APPARATUS FOR CONTINUOUS CASTING COMPRISING A LADLE, A MOLD ABOVE THE LADLE AND HAVING A VERTICAL PASSAGE THERETHROUGH FORMING A CAVITY, MEANS FORMING A PASSAGE FROM SAID LADLE TO AND COMMUNICATING WITH SAID MOLD CAVITY AT THE LOWER END THEREOF, SAID MOLD BEING OF HIGH HEAT CONDUCTIVITY RELATIVE TO THE LADLE AND PASSAGE FORMING MEANS, MEANS FOR APPLYING PRESSURE ON THE MOLTEN METAL IN THE LADLE FOR FORCING THE MOLTEN METAL THROUGH SAID PASSAGE AND INTO SAID MOLD, MEANS FOR CONTINUOUSLY WITHDRAWING THE CAST PRODUCT AT A CONSTANT RATE FROM THE UPPER END OF THE MOLD, AND MEANS FOR OSCILLATING THE MOLTEN METAL AND THEREBY RAISING AND LOWERING THE LEVEL THEREOF IN AND RELATIVE TO SAID MOLD, SAID AT MENTIONED MEANS BEING OPERATIVE FOR RAISING THAT LEVEL AT A RATE SUBSTANTIALLY EQUAL TO THE RATE OF WITHDRAWAL OF THE CAST PRODUCTS AND ABRUPTLY LOWERING THE LEVEL INDEPENDENTLY OF AND DURING THE CONSTANT WITHDRAWAL OF THE CAST PRODUCT. 